The present invention relates to a silicone-containing polyimide resin, a silicone-containing polyamic acid, and methods for manufacturing these. More particularly, it relates to a silicone-containing polyimide resin with superior heat resistance and flexibility, to a silicone-containing polyamic acid for which this polyimide resin is a raw material, and methods for manufacturing these.
Because of their excellent mechanical properties, heat resistance, and so on, polyimide resins are widely used as molding materials, films, and coating agents. In general, however, a polyimide resin has poor molding workability, flexibility, and solubility in solvents, so there has been proposed a method in which a polyorganosiloxane having amino groups at both ends of the molecular chain is copolymerized as a soft segment (see Japanese Laid-Open Patent Application 4-36321). Nevertheless, a problem with a silicone-containing polyimide resin obtained in this manner is that because the polyorganosiloxane chain is so long, low-molecular weight cyclic siloxane is generated by a cleavage reaction of the polyorganosiloxane chain under high temperature environments, the result of which is a decrease in heat resistance. Accordingly, there has been proposed a silicone-containing polyimide resin in which a disiloxane chain with two silicon atoms is copolymerized (see Japanese Laid-Open Patent Applications 58-27722 and 61-118424), but a drawback was that the two silicon atoms did not sufficiently improve flexibility. In light of this, there is a need for a polyimide resin with superior heat resistance and flexibility.
As a result of diligent study, the inventors arrived at the present invention upon discovering that the above problems can be solved by copolymerizing an organosiloxane having a specific chemical structure. Specifically, it is an object of the present invention to provide a silicone-containing polyimide resin with superior heat resistance and flexibility, a silicone-containing polyamic acid that serves as the raw material for this polyimide resin, and methods for manufacturing these.